It allows people to actually get things done. It allows them to spend less thought on the topics that are not concerned them in their day lives and spend more on their... day lives!
Basically, if you want people to go out of their cocoons, make their life easier. Otherwise, the fight is futile.
This works as long as the cocoon is perfectly insulated. But it isn't, as elections show. The political process basically cuts through the cocoon like a predatory wasp-- assuming there is at least one candidate or law that is incompatible with insulated beliefs. And then all that saved energy is wasted on moral warfare against the invaders.
Cocoons are always bad in a non-homogeneous society.
Sure, but "cocoons" breed intolerance by magnifying the fears and insecurities of the group. Maybe if you have balanced, open, secure people, blocking information doesn't hurt, but those people are not only rare, they tend to go out of their way for new information. They don't willingly slam the door on new streams of information so it seems their "cocoons" if they exist at all have fairly thin walls.
The most non-homegeneous society I know is New York.
I remember walking it and seeing Chinese area, black area, finance area, etc.
People always try to create bubbles around them with people they know they can trust. Or "facts" that supports their world view. Or familiar ideas. This all helps them spend less energy on "uninteresting" things.
And then they burn all that saved energy on moral warfare, raging furiously at non-threats. That's the problem.
If the past 200 years are any indication it won't make a difference.
And I mean easy when I speak about USSR. Life in contemporary Russia is much harder.